Internal Combustion Engines, Systems, Devices, and Methods for Propulsion and Power Applications

ABSTRACT

Engines, systems, devices, software, and methods of the present invention provide increased fuel efficiency and emission performance. The engine may include a magnesium alloy cast engine block cast as a mono-block with or without a ceramic inner core and including one or more cylinders designed to provide compression ratio of 10:1 to 14:1. Each cylinder may include one or more laser igniters, one or more supercritical fuel injectors configured to inject the fuel near or in a supercritical state, and carbon dioxide, which may be in the form of engine exhaust gas. The fuel may be diesel, gasoline, or other suitable hydrocarbons that may be cracked into smaller molecules prior to be injected into the cylinder.

CROSS-REFERENCE TO RELATED APPLICATIONS

The application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/476,465 filed Mar. 24, 2017, which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates in general to engines and morespecifically to hybrid compression-optical ignition engines, systems,devices, and methods for land, air, and marine propulsion and powerapplications.

Background Art

The benefits of diesel engine technology have long been established.Diesel engines are more rugged and reliable than their gasolinecounterparts: they are the most efficient power plant among all knowntypes of internal combustion (IC) engines, have a longer life, requireless maintenance, and have greatly reduced their fuel cost. Dieselengines typically burn about 30-50% less fuel than a gasoline engine ona per kilowatt (kW) basis, and they can burn both diesel and Jet-A(aviation) fuels. Depending on the application, they may operate onaverage for 15,000 to 30,000 hours before major maintenance or overhaulis required.

In many countries, diesel fuel is 50% less expensive than gasoline and70% less expensive than Jet-A fuel. Historically, 2-Stroke engines havebeen less expensive, both in terms of initial purchase and routinemaintenance, and are more flexible in application. Since 2-Strokeengines eliminate the valve train, the power-to-weight ratio is anexceptional advantage of 2-Stroke engines.

Diesel fuel is safer to store because it does not ignite as readily asgasoline, natural gas, or propane. It is intentionally difficult toignite at atmospheric pressure and almost impossible to igniteaccidentally. Because of its many benefits, diesel fuel has been thefuel of choice for internal combustion engines for the last severaldecades in Europe, Central & South America, Africa and Asia. Diesel fuelis widely available, throughout the world and most cost-effective, inthe current and future economic conditions. In the US, 25% of the cars,trucks and buses use diesel fuel. In Europe, 50% of registered passengercars use diesel fuel. In China and India, diesel represents 75% of thefuel used for road transportation. Furthermore, diesel fuel contains upto 30% more energy density per gallon than gasoline, which, in turnprovides greater fuel economy (33%) and much greater torque. This isgreatly needed for operation in dense environments like water, or forconstant hard-working cycles like power generators, helicopters,tiltrotors and boats, and it is much more efficient for hybrid(diesel/battery) powerplants combinations. Improving further theefficiency of diesel engines will reap huge environmental and economicbenefits.

However, despite the clear benefits, diesel engine technology haslargely been limited to specific land-based applications, such asautomobiles, locomotives, construction equipment, inboard marine, powergeneration, etc. Various well-known problems, such as noise andpollution, have rendered diesel engines generally unsuitable and/orundesirable for marine outboard, aviation engine, or motorcycleapplications, even though these markets are substantially larger thanexisting diesel markets. These markets require low weight,brake-specific fuel consumption (BSFC), packing, low emissions, andreduced noise.

Most approaches to applying diesel engine technology to theseapplications have involved applying automobile engine design, but thisapproach may be at the root of the failure for some applications.Correct engine packing and weight reduction are both essential forsuccess in these applications and may not be readily achieved withengines based on automobile technology. Applications specific engines,such as DeltaHawk aviation engine, as well as compressed natural gas(CNG) or hydrogen fuel cell solutions for the Medium and Heavy DutyCycle (“MHDC”) engine market may provide some relief. However, thereremains a significant demand for improved engines that address the needsof the marine outboard, piston aviation, and motorcycle industries.

Given that transportation and power demand is expected to continue toincrease, there is a continuing need for improved engines, systems,devices, and methods for propulsion and power applications for all fueltypes that deliver greater fuel efficiency and/or lower emission.

BRIEF SUMMARY OF THE INVENTION

Accordingly, engines, systems, devices, software, and methods of thepresent invention provide increased fuel efficiency and emissionperformance for propulsion and power applications. The engine mayinclude an engine block that is mono-cast using a magnesium alloy. Theblock may include a ceramic inner core, such as made from ceriastabilized tetragonal zirconia polycrystal (“CeTZP”) with the outsidemade from magnesium, and one or more cylinders suitable designed toprovide compression ratios of 10:1 to 15:1. Each cylinder may includeone or more laser igniters, one or more fuel turbocharged supercriticalfuel injectors configured to inject a mixture of a two-phased fuel nearor in a supercritical state and carbon dioxide, which may be in the formof engine exhaust gas. The fuel may be diesel, gasoline, or othersuitable hydrocarbons that may be cracked into smaller molecules priorto be injected into the cylinder.

As may be disclosed, taught, and/or suggested herein to the skilledartisan, the present invention addresses the need for improved engines,systems, devices, and methods for propulsion and power applications forall fuel types that deliver greater fuel efficiency and/or loweremission.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included for the purpose of exemplaryillustration of various aspects of the present invention, and not forpurposes of limiting the invention, wherein:

FIG. 1 illustrates various exemplary block diagrams of the system.

FIG. 2 illustrates various exemplary block diagram of the electroniccontrol unit.

In the drawings and detailed description, the same or similar referencenumbers may identify the same or similar elements. It will beappreciated that the implementations, features, etc. described withrespect to embodiments in specific figures may be implemented withrespect to other embodiments in other figures, unless expressly stated,or otherwise not possible.

DETAILED DESCRIPTION OF THE INVENTION

Systems, engines, devices, and methods of the present invention delivergreater fuel efficiency and/or lower emission for gasoline, diesel, andother fuel types used in propulsion and power applications.

In various implementations as shown in FIG. 1, the system 10 includes anengine block 12 configured to receive fuel and air (i.e., oxidizing gas)as inputs, combust the fuel in the presence of the air, and outputmechanical power and an exhaust stream including combustion products andresidual inputs.

The engine block 12 may have one or more inlets 14 _(1-N) that mayreceive fuel via one or more corresponding supercritical fuel injectors(SCFI) 16 _(1-M), which may be turbocharged (M and N being positiveintegers, which may or may not be the same value). The SCFI 16 providesfuel that may be a smaller or larger molecule fuel in a super-criticalor near super-critical state, and may be mixed with an amount of exhaustfrom the engine block 12. The amount and temperature of the exhaust thatis mixed with the fuel may be fixed or adjustable.

In various embodiments, the fuel can be mixed with other gases, such asvarious components of exhaust, carbon dioxide, carbon monoxide,nitrogen, nitrogen oxide, water vapor, incomplete combustion products,etc., individually or in various combinations. The exhaust and/or gasesgenerally functioning to 1) heat the fuel to proper temperature, and 2)dilute the fuel to help reduce the coking and incomplete combustion.

A fuel reconditioning system (FRS) 18 may provide the SCFI 16 withsmaller molecule (SM) fuel that has been produced by breaking largermolecule (LM) fuel received from a fuel source 20 into the smallermolecule fuel. Larger molecule fuels may include diesel, kerosene,gasoline, etc., and mixtures thereof. Whereas, smaller molecule fuelsmay include various shorter chain and smaller aromatic hydrocarbons,such as aliphatic hydrocarbons having a carbon chain length of 8 orless. It will be appreciated by one of ordinary skill that smaller isrelative to larger, so smaller molecules derived from breaking dieselfuel may be larger than smaller molecules derived from breaking gasolineand LM and SM fuel may include one or more different molecules.

A fuel heater 22 may be provided to receive the SM fuel exiting the FRS18, or LM fuel from the fuel source 20 in embodiments without the FRS18, and heat the fuel to supercritical or near supercriticaltemperatures. The fuel heater 22 may be an electric heater and/or a heatexchanger, such as shown in FIG. 1. The fuel heater 22 may beappropriately designed to heat the fuel to desired temperatures by askilled artisan.

In various embodiments, the fuel heater 22 may include one or more heatexchangers that use exhaust from the engine block 12 as a heating fluidthat enters the heat exchanger at an inlet temperature TIN and exits theheat exchanger at an outlet temperature of TIN minus delta T.

In various embodiments, an exhaust splitter 24 may be provided to splitan exhaust stream output from the engine block 12 that is provided asinput to the splitter 24 into two or more output exhaust streams. Theoutput exhaust streams may be provided to the fuel heater 22 to providethe heating fluid as described above. The exhaust splitter 24 may be apipe section with one inlet and two or more outlets or a morecomplicated design as desired by the skilled artisan. In variousembodiments, the amount of exhaust output to each of the two or moreexhaust output streams may be adjustable or fixed.

A mixer 26 may also be provided to mix one or more of the output exhauststreams from the exhaust splitter 24 with the heated SM or LM fuelcoming from the fuel heater 22. In FIG. 1 embodiments, the mixer 26 isdepicted as being before the SCFI 16; however, the mixer 26 may beintegrated with the SCFI 16 or provided after the SCFI 16. In addition,the mixer 26 is shown in FIG. 1 as receiving an output exhaust streamthat is separate from an output exhaust stream being provided to thefuel heater 22. However, the outlet exhaust stream provided to the fuelheater 22 may also be mixed with the fuel stream. The mixer 26 may be apipe section with two or more inlets and one outlet or a morecomplicated design as desired by the skilled artisan.

Furthermore, FIG. 1 depicts the SCFI 16, fuel heater 22, and mixer 26 asseparate units. However, these units can be integrated into one or moreunits and/or maintained as separate units, but packaged together in oneor more packages.

The system 10 may include a high energy optical ignition source, such asa multipoint laser ignition (MLI) system, 28 configured to provide laserignition of the fuel by delivering light, i.e. laser beam(s), in one ormore cylinders of the engine block 12. In various embodiments, the MLIsystem 28 may be configured such that one or more lasers may be providedproximate to the cylinder in which the lasers are being used to ignitethe fuel. The light emitted by the one or more lasers may be deliveredinto the cylinders via one or more ignition ports.

In various embodiments, one or more lasers may be positioned remote fromthe engine block 12 and the optical energy provided by the lasers may bedelivered by optical fiber to the engine block 12. Placing the opticalsources remote to the engine block 12 may enable the optical sources tobe placed in an environment that is more operationally favorable to thelife expectancy of the optical source. Two or more lasers may be used toprovide power to each cylinder and the optical power from the multipleoptical sources may be combined and then split and provided to multipleignition ports. Combining and splitting optical power from multiplelight sources provides redundancy and a graceful failure mode for theMLI system 28.

The system 10 may include one or more electronic control units (“ECU”)30 that may monitor and/or control one or more of the SCFI 16, FRS 18,fuel heater 22, exhaust splitter 24, mixer 26, and MLI system 28. TheECU 30 may be positioned proximate or remote from the engine block 12and may be positioned proximate to the MLI system 28.

FIG. 2 illustrates exemplary embodiments of the electronic control unit(ECU) 30, which may include one or more processors 80, memory 82,storage 84, input components 86, output components 88, communicationinterfaces 90, as well as other components that may be interconnected asdesired by the skilled artisan via one or more buses 92. In variousembodiments, the ECU 30 may include a built-in “get-home” capability bybeing designed with multiple layers within it, so if one layer burns outor is damaged, any of the remaining layer(s) keeps the device operatingthus providing a very elevated level of redundancy.

Processor(s) 80 may include general purpose processors, centralprocessing units (CPUs), graphics processing unit (GPUs), acceleratedprocessing units (APUs), microprocessor, and/or any processingcomponent, such as field-programmable gate array (FPGAs),application-specific integrated circuit (ASICs), etc.) that interpretand/or execute instructions. The processor(s) 80 may contain a cachememory unit for temporary local storage of instructions, data, orcomputer addresses and may be implemented as a single-chip, multiplechips and/or other electrical components including one or moreintegrated circuits and printed circuit boards that implements andexecutes logic in hardware, in addition to executing software.

Processor(s) 80 may connect to another unit or computer system, or totelecommunications network as part of performing one or more steps ofone or more processes described or illustrated herein, according toparticular needs. Moreover, one or more steps of one or more processesdescribed or illustrated herein may execute solely at the processor 80.

The system 10 may implement processes employing hardware and/or softwareto provide functionality via hardwired logic or otherwise embodied incircuits, such as integrated circuits, which may operate in place of ortogether with software to execute one or more processes or one or moresteps of one or more processes described or illustrated herein. Softwareimplementing particular embodiments may be written in any suitableprogramming language (e.g., procedural, object oriented, etc.) orcombination of programming languages, where appropriate.

Memory 82 may include a random access memory (RAM), a read only memory(ROM), and/or another type of dynamic or static storage device, such asflash, magnetic, and optical memory, etc. that stores information and/orinstructions for use by processor 80. The memory 82 may include one ormore memory cards may be loaded on a temporary or permanent basis.Memory 82 and storage 84 may include an ECU identification module.

Storage component 84 may store information, instructions, and/orsoftware related to the operation and use of the ECU 30. Storage 84 maybe used to store operating system, executables, data, applications, andthe like, and may include fast access primary storage, as well as sloweraccess secondary storage, which may be virtual or fixed.

Storage component 84 may include one or more transitory and/ornon-transitory computer-readable media that store or otherwise embodysoftware implementing particular embodiments. The computer-readablemedium may be any tangible medium capable of carrying, communicating,containing, holding, maintaining, propagating, retaining, storing,transmitting, transporting, or otherwise embodying software, whereappropriate. The computer-readable medium may be a biological, chemical,electronic, electromagnetic, infrared, magnetic, optical, quantum, orother suitable medium or a combination of two or more such media, whereappropriate. The computer-readable medium may include one or morenanometer-scale components or otherwise embody nanometer-scale design orfabrication. Example computer-readable media include, but are notlimited to fixed and removable drives, application-specific integratedcircuits (ASICs), CDs, DVDs, field-programmable gate arrays (FPGAs),floppy disks, optical and magneto-optic disks, hard disks, holographicstorage devices, magnetic tape, caches, programmable logic devices(PLDs), random-access memory (RAM) devices, read-only memory (ROM)devices, semiconductor memory devices, solid state drives, cartridges,and other suitable computer-readable media.

Input components 86 and output components 88 may include various typesof input/output (I/O) devices. The I/O devices may include varioussensor inputs and control lines associated with the operation of theengine, graphical user interfaces (GUI) for system setup andtroubleshooting, location information via global positioning system(GPS) or otherwise, accelerometer, gyroscope, actuator data, and otherinput received via one or more communication interfaces 90. Outputcomponent 88 may also include displays, speakers, lights, and otherdevices used to provide information to users and/or other systems.

Communication interface 90 may include one or more transceivers,receivers, transmitters, modulators, demodulators that enablecommunication with other systems and devices, via wired and/or wirelessconnections. Communication interface 90 may include personal and localarea network interfaces, such as Ethernet, optical, coaxial, universalserial bus (USB), infrared, radio frequency (RF) including Bluetooth,Wi-Fi, WiMax, etc., as well as wide area network, cellular-basedcommunication protocols such as 3G, 4G, 5G, AMPS, CDMA, TDMA, GSM(Global System for Mobile communications), iDEN, GPRS, EDGE (EnhancedData rates for GSM Evolution), UMTS (Universal Mobile TelecommunicationsSystem), WCDMA and their variants, among others, as described herein andknown in the art.

Bus 92 may connect a wide variety of other subsystems, in addition tothose depicted in FIG. 2, and may include various other components thatpermits communication among the components in the system 10. The bus 92may encompass one or more digital signal lines serving a commonfunction, where appropriate, and various structures including memory,peripheral, or local buses using a variety of bus architectures. As anexample and not by way of limitation, such architectures include anIndustry Standard Architecture (ISA) bus, an Enhanced ISA (EISA) bus, aMicro Channel Architecture (MCA) bus, a Video Electronics StandardsAssociation local bus (VLB), a Peripheral Component Interconnect (PCI)bus, a PCI-Express (PCI-X) bus, and an Accelerated Graphics Port (AGP)bus.

The system 10 may provide functionality as a result of the processors 80executing software embodied in one or more computer-readable storagemedia residing in the memory 82, and or storage 84 and logic implementedand executed in hardware. The results of executing the software andlogic may be stored in the memory 82 and/or storage 84, provided tooutput components 88, and transmitted to other devices via communicationinterfaces 90. In execution, the processor 80 may use various inputsreceived from the input components 86 and/or the communicationsinterfaces 90. The input may be provided directly to the processor 80via the bus 92 and/or stored before being provided to the processor 80.Executing software may involve carrying out processes or steps mayinclude defining data structures stored in memory 82 and modifying thedata structures as directed by the software.

In various embodiments, the system 10 may employ a scalable enginearchitecture (SEA) concept, in which parts of the system 10 may bedesigned to be used in multiple system configurations. SEA lowersstocking costs and substantially reduces the costs of manufacturing,assembly and replacing spare parts. Common parts may be more affordableand more suitable for use in reconfigurable and automated assemblylines. SEA also reduces the training burden and enables personnel todevelop widely applicable skills. The benefits of SEA may result in highquality, lower cost parts and finished goods.

In various embodiments, a compact engine architecture (CEA) may allowthe engines to be packed in a manner suitable for the four majorapplications without any substantial modifications. It also allowsadditional features and systems to be added for particular applications

In various embodiments, the engine block 12 includes a light-weightmetal block, such as a magnesium alloy cast as a mono-block. Magnesiumalloys may be 33% lighter than aluminum and, if alloyed using cathodicsolution techniques, may have acceptable corrosion and high temperaturecreep resistance. For example, stainless magnesium alloys produced bymeans of adding a cathodic solution to the magnesium alloy duringmelting of the ingots in the furnace for engine block casting to preventthe bonding of the hydrogen atoms, appear to reduce corrosion, when thecathodic solution is added in percentages from 0.5% to 2.5% of the totalalloy weight percentage. Additionally, the casting system may be fullyenclosed from the melting furnace to the casting mold(s) to reduce airexposure may further reduce corrosion. Other properties of these Mgalloys also appear suitable for engine block use, such as tensilestrength, heat resistance, bolt retention, good flowing characteristicsfor casting, shock absorbency, damping capacity, and electromagneticinterference (EMI) shielding.

The engine block may also be produced with an inner core made ofsuitable ceramic materials, such as ceria stabilized tetragonal zirconiapolycrystal (CeTZP) with the outside made from magnesium. The ceramiccore may further reduce the heat loss from the combustion chamber due tothe CeTZP ceramic exceptional low thermal conductivity of 1.9 w/m·k,which may enable the engine to deliver the same horsepower with 50% lessdisplacement and fuel consumption. Also, the low thermal conductivity ofceramics may allow the engine to operate with lower coolingrequirements. Furthermore, the ceramic allows high operatingtemperatures (possibly >800° C.), compared to cast iron (<600° C.),steel (<500° C.), and aluminium alloys (<300° C.), which may deliverincreased combustion efficiencies and more complete combustion relativeto traditional engine materials. Lastly, the CeTZP and other ceramicsmay be less prone to hydrothermal degradation.

Another advantage of producing the monoblock using a CeTZP inner core,is the overall reduction of the engine dimension by >40%. The reductionof the overall dimensions further reduces material costs and weight. A100% CeTZP ceramic made engine has been tested on a small test rotaryengine configuration performing very well. Additionally, CeTZP ceramictends to be very resistant to environmental degradation associated withchemicals associated with internal combustion engines, which is a majorstumbling block up to now to use ceramics in internal combustion enginedesign.

The engine internal components may also be made from lighter weightmetals, such as light-weight steel, titanium (Ti), and/or aluminum (Al).For example, crankshafts, pins, and dowels can also be made from aspecial light-weight steel (6.8 g/cm3), which is not only 17% lighterthan normal steel (7.8 g/cm3), but has better ductility, a slightlyhigher tensile strength, and a capacity to be heat-treated to RC 70without becoming brittle.

In various embodiments, Ti may be to reduce weight or size for shafts,pins, conrods and other similar parts. Additionally, the heat-treatmentof Ti can now be done upwards of Rc 70, and to its core, withoutbecoming brittle and tensile strength in some grades has been increasedto 1,750 MPa, which may increase the suitability for these applications.

Ultra-strong aluminum alloys, such as A-1500 with a tensile strength of1.2 GPa and Young's Modulus is superior to titanium may also be used tomake conrods, crankshafts, and other parts further reducing the steelcontent and weight of the engine. The reduced weight may allow forbetter-balanced diesel engines by reducing reciprocating forces.

In various embodiments, the engines may be packed to fit both marine andaviation applications, which require the tightest overall dimensions, toenable the same engine to be used in multiple applications. Engines maybe configured to operate in one, some, or all orientations, e.g.,upright, sideways or upside down. The blocks may have built-in mountingholes to enable custom or application specific hardware to be attachedduring assembly.

Moving and coated engine parts may be cryogenically treated, eitheremploying a standard nitrogen refrigeration or a new magneticrefrigeration process that delivers superior results, which tightens themetal crystals into a very compact structure increasing hardness andlowering porosity to improve wear and fatigue properties. The engineblock may be externally coated with pure aluminum, to enhance long-termprotection. Internal coatings may employ a diamond-like coating (DLC) ortetrahedral amorphous carbon (Ta-C) coating, to provide lower frictionand high hardness. Replaceable DLC-coated cylinder liners may beemployed to extend the useful life of the engine block, allowingmultiple total basic overhauls (TBOs). Piston rings will have the facesurface coated with Ta-C diamond for super hard and exceptional longlasting operating time before replacement.

A substantial percentage of weight concentration in a diesel engine isin the engine block and cylinder head. Casting the engine block 12 as amono-block, instead of the traditionally separated cylinder head andblock, may reduce the combined weight of the engine block and internalparts compared to any current diesel engines or even 4-Stroke gasolineengines. Engines of the present invention, may be designed with a weightratio of below 0.40 lb/HP for various applications. This refers to themain engine alone for marine applications and the ready-to-mount enginefor aviation applications, excluding any gear-housing or transmission.Gear-housings and transmissions may also be made of the same magnesiumand other alloys to further reduce weight.

For the internal components, an average weight reduction may be around33% if lighter weight parts are used with lower compression designs. Asfor reciprocating parts, the weight of the pistons and conrods may bereduced by 25%, which may reduce mechanical friction and parasiticlosses of energy for diesel engines to below that of an average gasolineengine. The reduced weight may also provide better engine balancing.

In various embodiments, the engine may employ fewer cylinders thantraditional engines for comparable power and may be designed with manycommon parts. For example, manufacturers of gasoline marine outboard andpiston aircraft engines use 3 and 4 cylinders for engines of 25 HP to200 HP and 6 to 8 cylinders for engines of 225 HP and above. In variousembodiments, the invention may support 2 cylinders for engines of up to100 HP, 3 cylinders for 75 HP up to 400 HP, and 6 cylinders from 350 HPto 800 HP. This will provide excellent production and retail costsavings and exceptional high number of common parts and weightreduction.

Engines of the present invention may be operated at low compression toallow superior optimization of combustion timing. In low compressionengines, compression temperature and pressure decrease at the top deadcenter (TDC). While this lower temperature makes the ignition takelonger when fuel is injected near the TDC, it enables a better mixtureof air and fuel. This results in a highly efficient diesel engine inwhich a higher combustion expansion ratio is obtained. The higherexpansion ratio prolongs the delivery of torque to the drivetrain.Conversely, current high-compression diesel engines only deliver ashort, super strong force to the drivetrain, which may be destructive.Low compression makes it possible to deliver high torque throughout theexpansion of the piston, which yields greater efficiency. With lowcompression, the engine exhibits a flatter torque line, which means thatit has high torque from the low end to the high end of the RPM (Rotationper Minute) engine range.

Low compression also substantially reduces the formation of NOx andsoot, the main causes of diesel pollution and black smoke. In lowcompression engines, localized high-temperature areas and oxygeninsufficiencies may be reduced to improve combustion uniformity andefficiency. Target specifications for various embodiments may be lessthan 0.001 g/km of fsDPM (particulate) and 0.001 g/km of fsNOx, based onindependent testing by Sandia National Laboratory.

Cold-start ignition of diesel and other fuels may be accomplished usinghigh temperature ceramic igniters (ceramic glow plugs) and multi-holepiezo injectors, or using the MLI system 28.

Supercritical fuel injectors 16 may significantly reduce fuelatomization and droplet vaporization (slow burning process), which mayincrease combustion efficiency. In various embodiments, the SCFI 16 mayoperate in a range including 2,000 bar, which may improve the cost andperformance of the SCFI relative to high pressure systems operatingaround 3,000 bar or higher. The SCFI may include a choke, whichresembles a de Laval nozzle, to accelerate the velocity of the gascontent of the two-phase fuel, to permit the gas content in the fuel toachieve supersonic velocity during injection. It will be appreciatedthat the nozzle may be varied to accommodate different types of fuel.

Since diesel is heavy, viscous, and less volatile than gasoline, not allthe fuel is burned during combustion, which results in higher levels ofparticulate soot. The higher combustion temperatures for diesel alsoresults in increased NOx emissions. By raising diesel to a supercriticalstate, and/or breaking it into smaller molecules, before the fuel isintroduced into the combustion chamber of the engine block 12, viscositybecomes less of a problem. Additionally, the high molecular diffusion ofsupercritical fluids means that the fuel and the air mix together muchmore rapidly with air enabling the fuel to combust more quickly,cleanly, and completely. An important advantage of SCFI is that itsubstantially lowers the surface tension of the fuel, providing positiveadvantages in better combustion and adding to cleaner emissions.

In various embodiments, exhaust gases (EG) may be used to heat the fuelin a heat exchanger (HE). It is generally desirable to maintain the fueltemperature in the range of 560-580° C. EG flow rates may be regulatedvia electrically operated valves controlled by the ECU 30 usingtemperature sensors positioned in the fuel rails of the HE to controlthe fuel temperature. The heated fuel exits the HE and passes to theSCFI.

Engine emissions using SCFI may be reduced by 80% in a high compression18:1 engine and possibly more than 90% in low compression engines of thepresent invention, which may result in 10-30% fuel reduction. SCFI testwere performed by Sandia National Laboratories and National Institute ofStandards and Technology (NIST).

While SCFI may provide significant benefits, for larger molecule fuels,such as diesel, it may be desirable to mix EG with the fuel to reduce,and preferably eliminate, coking of the fuel in the fuel injector.Mixing may take place either before or after pressurizing the fuel tothe final injection pressure desired. If the process to bring the fuelto super critical state takes place before being pressurized, the fuelpump may need to a two-phased fuel pump, to permit operation with atwo-phased fuel to accommodate changes in state.

The MLI system 28 of the present invention may enable more preciseignition of the fuel mix at a precise crankshaft angle (or pistonposition) in each cylinder individually. Prior art compression ignitionengines are limited in precision due to as-built and wear factorscreating variation in design and operation, which is likely to varybetween cylinders and with different diesel fuel compositions.

The present invention addresses problems that exist with deployment ofMLI systems in prior art engines, which involve fouling of the laserinput to the engine block 12, thus impacting the reliability of the MLIsystem to ignite the fuel. In the present invention, the SCFI, lowcompression, and other features serve to reduce the soot and otherincomplete combustion products that may foul laser input port(s) intothe cylinder. In addition, the lasers used in the MLI system 28 mayinclude a lense coating with a damage threshold greater than 3 GW/cm2enabling the laser to provide some level of self-cleaning.

The MLI system 28, as with other systems described herein, may becontrolled by the engine's electronic control unit (ECU) to enableprecise ignition of the fuel that may be optimized during operation.Engine timing information may be provided from sensors mounted on thecrankshaft to permit the precise crankshaft angle position for firingthe laser. This is in stark contrast to current diesel enginetechnology, where ignition of the fuel depends on compression andtemperature which it may vary after each injection. The ECU 30 may alsocontrol various other systems, such as electronic superchargers andelectric drive pumps.

The MLI system 28 may be very suitable for low compression fuel ignitionand very effective at igniting diesel and other fuels at extreme lowtemperatures. Additionally, laser ignition may significantly increasecombustion timing due to the light, or laser beam(s), emitted by thelaser(s) that is providing the ignition energy is moving at the speed oflight, rather than only conduction and convection. Increased combustionrates may increase combustion efficiency, thereby reducing pollutantsresulting from incomplete combustion. The ignition laser beam also addsenergy to the fuel. And the MLI system breaks the molecule from insideunlike traditional ignition of fuels, making the combustion moreefficient and more total.

MLI systems 28 may be employed in various patterns such aspre-injection, main injection and post-injection, to improve cold-startand other capability. Each injector may be controlled individually bythe ECU 30, which may be used to tune each cylinder as desired toimprove balance and other factors. The MLI system 28 may be employed indifferent embodiments. For example, the MLI system 28 may use a singlecontroller box with optic fiber cables and a laser plug to distributethe laser beam(s) to each individual cylinder according to the firingorder. Another system uses an individual laser for each cylinder in aself-contained unit with the firing of each individual unit on eachcylinder controlled by the engine ECU. Also, the lens on each laser plugmay deliver 3 to 4 laser beams into each cylinder by splitting thereceiving main beam, to generate multiple flame fronts and furtheraccelerate combustion, which further increases efficiency and cleanerexhaust gases. The lens in the laser plug may be made from sapphire orother dedicated material.

The MLI system 28 may enable the engines of the present invention tooperate with an extremely lean fuel mixture (>85:1) and for fuelignition at a wide range of temperatures, with reduced misfiring.Independent test with high pulse energy, e.g., 25 mJ, and short pulselengths (less than 3 ns) was able to initiate optical breakdown at focallengths of up to 80 mm and reliable ignition in both stratified andhomogenous fuel modes.

The Fuel Reconditioning System 18 may be employed to reduce themolecular size of the fuel by breaking, or “cracking”, the fuel intosmaller molecules, which typically will increase the combustionefficiency of the fuel, other factors being the same. The FRS 18 may beembodied as a high-voltage electric current device operating at aspecified frequency and wavelength. It can also employ severalfrequencies and wavelengths to better adapt to the different sizes ofthe broken molecules which come from each “cracking”. At each“cracking”, each broken portion of the molecule increasingly becomessmaller. It is desirable to make each broken piece as small as possibleto increase the combustion velocity, which in turn releases highercombustion energy. The FRS process may be applied before the fuel isbrought to supercritical state and after the fuel is pressurized, toproperly take in account the state of the fuel molecules, to preventtaking other shapes once either the “cracking” or SCFI process isemployed, as the fuel moves from one process to the other prior toinjection.

FRS testing with Tier 3 rated diesel engines has shown that it mayprovide various system benefits, such as increased fuel volatility,density and pressure, and decreased boiling point. The net result may bethat the SM fuel combusts more completely and rapidly, and at lowertemperatures, which may produce more horsepower per unit of fuel burned,reduce fuel consumption, and distribute power more evenly for smootherperformance.

In various embodiments, the engines may be supercharged or crankcaseaspirated. For example, it may be desirable to equip engines with powerratings of 75 HP and higher with one or more superchargers. Thesuperchargers may be electricity-driven and controlled by the ECU 30 forthe highest performance throttle response, especially when acceleratingfrom being idle (i.e. “out of the hole” throttle response), whichreduces lagging. Supercharged engines may provide more than 100 HP perliter, and potential more than 200 HP per liter. Crankcase aspiratedengines performance may be controlled by electronically controlling theair and fuel management via the ECU. The electric power may be providedby a battery or a water-cooled exhaust-driven generator(s) (6-7 KW) or aradiant generator.

In various embodiments of the engine system 10, a magnesium alloy engineblock 12 cast as a mono-block with or without a ceramic inner core isprovided to receive fuel and air as input into one or more combustionchambers/cylinders, where the fuel is combusted, and power and exhaustare output. A fuel reconditioning system 18 breaks down at least aportion of a larger molecule fuel into a smaller molecule fuel. Exhaustfrom the engine block 12 is provided to a heat exchanger 22 to heat thesmaller molecule fuel. A mixer 26 is provided to mix exhaust with theheated smaller molecule fuel to produce an exhaust-supercritical fuelmixture, which is injected via supercritical fuel injectors 16 intoengine block 12. The supercritical fuel mixture is compressed in theengine block and ignited via an optical ignition system, such as amulti-point laser ignition system, to combust the fuel with air andexhaust exits the engine block. An electronic control unit 30 controlsthe overall operation of the engine, at least one of the other steps.

For example, in various embodiments, the electronic control unit 30includes memory and one or more processors to monitor, typically fromsensor feedback, and control the breaking down of at least a portion ofthe larger molecule fuel into the smaller molecule fuel, heating of thesmaller molecule fuel to a supercritical temperature, mixing of exhaustwith the heated smaller molecule fuel to produce anexhaust-supercritical fuel mixture, injection of theexhaust-supercritical fuel mixture in the cylinder of the engine block,and the timing of the compression, ignition, and combustion of the fueland exhausting the combustion products from the engine.

As described above, while an order of operation has been provided, itwill be obvious to one of ordinary skill that various steps may berearranged, broken into multiple steps, and potentially eliminateddepending upon the particular application and fuel. For example,gasoline retrofit engines and methods of the present invention mayinvolve replacing one or more spark plugs with a laser or other opticalignition system. One or more supercritical fuel injectors may be addedto the fuel intake of the engine to inject an exhaust-supercritical fuelmixture into the engine. A fuel reconditioning system may be installedbetween the supercritical fuel injectors and a fuel source to breaklarger molecule fuel into smaller molecule fuel. A mixer and heatexchanger and associated plumbing may be provided to combine the smallermolecule fuel and exhaust from the engine to provide theexhaust-supercritical fuel mixture to the supercritical fuel injectors.

Depending upon the engine being retrofitted according to the presentinvention and the intended application(s), various steps of theprocesses and elements may be eliminated and other added as appropriate.For example, it may not be necessary to employ SCFI in someimplementations or to employ a separate heat exchanger before mixing theexhaust with the fuel. When smaller molecule fuels are the fuel supply,it may not be necessary to employ an FRS 18. Person of ordinary skillwill be able to envision and practice other variations that are withinthe scope of the invention for newly built engine and retrofitapplications.

For the aviation application, by means of continuously adjusting toaltitude pressure, the supercharger may be particularly useful in therange of 450 to 1,200 HP in takeoff, climbing and at-altitude engineperformance. The superchargers may continuously deliver the maximumpower possible at sea level at altitudes from sea level up to andincluding 28,000 feet, unlike many turbines which degrade in performanceat higher altitudes.

In various embodiments, the engines may be gas-cooled or liquid-cooled,e.g., air, water. In many embodiments, fresh water may be an appropriatecoolant. For aviation use, liquid-cooling translates into lower thermalvariance, which reduces engine block cracking especially after landingin very cold environments. For marine use, closed-loop coolingeliminates the problem of salt-water since no salt water gaets insidethe engine, a big problem with marine outboard engines.

In various embodiments, engines of the present invention may achieve10,000 hours of operational life for high RPM applications before theneed for overhaul and 15,000 hours for the low RPM applications. Priorart engines may only achieve 1,500 hours of operational life, onaverage, for current 4-Stroke gasoline engines in the marine, pistonaviation and gasoline generator applications.

Various embodiments may achieve lower RPMs, e.g., 5,500 RPMs for the I-3block, and 3,000 RPMs for the V6 or larger blocks, which may reduce theamount of wear and tear on the engine, while providing a flat torquecurve than current gasoline engines. This is excellent for generatingelectrical power in the marine environment, for aircraft applications orfor drones. Higher-amps electronic onboard generators can be available,especially to supply power for Synthetic Aperture Radars in UAVs andenergy-based systems that are ever smaller but have increasing energydemands.

Furthermore, the present invention is compatible with various hybridelectric technologies and batteries, including lithium and magnesiumbased batteries. Various embodiments of the system 10 may include a 48-Velectrical architecture and/or voltage regulators for existing 12 V or24 V systems.

Various other technologies and design choices may be employed to reduceparasitic power losses and improve performance. These technologiesinclude, for example, electric-drive water and oil pumps andsuperchargers, exhaust-driven generators, the use of only onecompression ring and one oil ring, improved piston-rings to reduce oilsloshing, advanced coatings, such as silicon-reinforced porous aluminum,offset crankshafts, oil heaters, high-output high-density alternatorsand radiant generators.

Diesel engines of the present invention may support both propulsion andelectric power for marine applications. As many recreational boatscurrently have one gasoline tank for the engine, and one diesel tank foran on-board electrical generator, the present invention would allowmanufacturers to eliminate one fuel tank and/or increase the amount offuel carried.

Various marine applications may require additional features, such as thecapability to operate with forward-facing or rear-facing propellers,flywheel-mounted electric starter, closed-loop cooling to avoidcorrosion from salt water, built-in electric steering with trim & tilt,under-water exhaust, tiller, carbon fiber or graphene panels for theexternal panel covering, etc. An electrical engine may be included foroutboard marine applications to extend stealth trolling and portoperations with near-zero fuel use. An electric motor may be directlyassembled onto the transmission housing in order to reduce both weightand excess parts and also may function as a starter.

Digital throttle control may be included for all outboard engines 55 HPand above and optional below 55 HP. A digital joy-stick will beavailable with several driving modes and will be pre-loaded. In someembodiments, a horizontal crankshaft layout with a right-anglecomputer-controlled transmission may be employed. Gear shifting may takeplace in the transmission, instead of the lower drive in order toeliminate the typically problematic area of traditional outboardpropulsion systems.

Additionally, a unique twin-pinion gear design in the torpedo lower gearcase may be employed to address a traditional weakest point in outboarddesign. Current outboard engines use only one pinion shaft to distributethe torque load and support high stress loads, which is very hard onoutboard engines especially during re-entry into water after goingairborne. With the two-gear design, the stress is cut in half. Acollapsible, failsafe design for the lower drive may be, in order tosave the engine from any major underwater hit.

Software and gyroscopes may interface with the automated trim tabs toprovide the engines with continuous automatic electric control of theengine tilt. This automatic process continuously controls theadjustment, e.g., thousands of times per second, of the boat's enginetilt and both independent trim tabs, from the start and throughoutoperation in any sea condition at any speed. Automatic control of eachtrim tab independently may help to level off the boat, should the weightonboard not be properly distributed. The software may also interfacewith GPS units and auto-pilot navigation systems.

Aviation applications may include various features, such as a singlethrottle lever control without fuel mix manual control to reduce engineblow-out risk and lower exhaust gas temperature (EGT). A dual-channelFADEC system may be employed and pressure adjustable superchargers.Since diesel and Jet-A fuel have the same ignition temperature (˜400°F.) in-flight refueling is possible for small- to medium-weight UAVs,substantially increases possible airborne time as well as the operatingcapabilities of each aircraft, like range and flight endurance. Inaddition, engines of the present invention are not cycle limited, justengine TBO making short to medium range aviation more cost effective.Foam filtration of diesel fuel may be employed as well as fuelcirculation with heating. Infrared (IR) signature suppressors on engineexhausts may be included for military applications.

For MHDC land vehicle applications, engines of the present invention maysupply a total power output of 2,000 HP to 3,000 HP directly to thewheels under an All-Wheel drive mode, making them capable of movingtrucks weighing over 120,000 lbs, as well as higher payloads.Independent motors may be placed on each side of the axles to enableconstant automatically adjusted power output and individual control forexceptional traction and safety under adverse conditions.

Active gradient control (AGC) for descending operation, each wheel mayprovide continuous regenerative energy to help recharge the batteries inhybrid embodiments. The AGC can provide constant speed in all types ofterrain, especially high gradient terrain (i.e. uphill) where currenttrucks suffer greatly from exceptionally low fuel economy.

For power generator applications, the ECU 30 may be configured toprovide unique throttle control to regulate the engine throttleaccording to electrical output demands, which is in contrast to currentgenerators that operate on only two levels—either idling or working atfull throttle.

Since 2-Stroke diesel engines execute four power pulses per revolutionand operates at low compression, engines of the present invention cansupply a longer continuous positive torque to the piston, and therefore,much more force to the shaft. Additionally, Inline and tight “V” and “W”configurations allow the engines to be mounted in any position forrepower aviation applications. Single piston can be as light as a2-Stroke gasoline engine with same HP.

The foregoing disclosure provides examples, illustrations anddescriptions of the present invention, but is not intended to beexhaustive or to limit the implementations to the precise formdisclosed. Modifications and variations are possible in light of theabove disclosure or may be acquired from practice of theimplementations. These and other variations and modifications of thepresent invention are possible and contemplated, and it is intended thatthe foregoing specification and the following claims cover suchmodifications and variations.

As used herein, the term component is intended to be broadly construedas hardware, firmware, and/or a combination of hardware and software. Itwill be apparent that systems and/or methods, described herein, may beimplemented in different forms of hardware, firmware, or a combinationof hardware and software. The actual specialized control hardware orsoftware code used to implement these systems and/or methods is notlimiting of the implementations. Thus, various operations and behaviorsof the systems and/or methods may be described herein without referenceto specific software code or specific hardware. One of ordinary skillwill appreciate that software and hardware may be designed to implementthe systems and/or methods based on the description herein.

Hardware processor modules may range, for example, from general-purposeprocessor to a field programmable gate array (FPGA) to an applicationspecific integrated circuit (ASIC). Software modules (executed onhardware) may be expressed in a variety of software languages (e.g.,computer code), including C, C++, Java™, Javascript, Rust, Go, Scala,Ruby, Visual Basic™, FORTRAN, Haskell, Erlang, and/or otherobject-oriented, procedural, or other programming language anddevelopment tools. Computer code may include micro-code ormicro-instructions, machine instructions, such as produced by acompiler, code used to produce a web service, and files containinghigher-level instructions that are executed by a computer using aninterpreter and employ control signals, encrypted code, and compressedcode.

Some implementations are described herein in connection with thresholds.As used herein, satisfying a threshold may refer to a value beinggreater than the threshold, more than the threshold, higher than thethreshold, greater than or equal to the threshold, less than thethreshold, fewer than the threshold, lower than the threshold, less thanor equal to the threshold, equal to the threshold, etc.

Certain user interfaces have been described herein and/or shown in thefigures. A user interface may include a graphical user interface, anon-graphical user interface, a text-based user interface, etc. A userinterface may provide information for display. In some implementations,a user may interact with the information, such as by providing input viaan input component of a device that provides the user interface fordisplay. In some implementations, a user interface may be configurableby a device and/or a user (e.g., a user may change the size of the userinterface, information provided via the user interface, a position ofinformation provided via the user interface, etc.). Additionally, oralternatively, a user interface may be pre-configured to a standardconfiguration, a specific configuration based on a type of device onwhich the user interface is displayed, and/or a set of configurationsbased on capabilities and/or specifications associated with a device onwhich the user interface is displayed.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of possible implementations. In fact,many of these features may be combined in ways not specifically recitedin the claims and/or disclosed in the specification. Although eachdependent claim listed below may directly depend on only one claim, thedisclosure of possible implementations includes each dependent claim incombination with every other claim in the claim set.

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Furthermore,as used herein, the term “set” is intended to include one or more items,and may be used interchangeably with “one or more.” Where only one itemis intended, the term “one” or similar language is used. Also, as usedherein, the terms “has”, “have”, “having”, or the like are intended tobe open-ended terms. Further, the phrase “based on” is intended to mean“based, at least in part, on” unless explicitly stated otherwise.

The presence or absence of a summary, abstract, or claims in thisapplication should in no way be considered as limiting on the scope ofany inventions disclosed herein.

What is claimed is:
 1. A system comprising: a magnesium alloy engineblock cast as a mono-block to receive fuel and air as input compress thefuel and air to a compression ratio of at least 10:1 and less than 15:1,combust the fuel, and output power and exhaust; a fuel reconditioningsystem to receive fuel, and break down at least a portion of the dieselfuel into smaller molecule fuel; an exhaust splitter to split theexhaust into two or more exhaust streams; a heat exchanger to heat thesmaller molecule fuel using at least one of the exhaust streams, a mixerto combine exhaust from at least one of the exhaust streams with heatedsmaller molecule fuel to produce an exhaust-supercritical fuel mixture;one or more supercritical fuel injectors to inject theexhaust-supercritical fuel mixture into engine block; a multi-pointlaser ignition system to ignite the smaller molecule fuel in the engineblock; and, an electronic control unit to control the fuelreconditioning system, heat exchange, mixer, exhaust splitter, fuelinjectors, and laser ignition system.
 2. The system of claim 1, wherethe engine block has a ceramic inner core.
 3. The system of claim 2,where the ceramic inner core comprises a ceria stabilized tetragonalzirconia polycrystal.
 4. The system of claim 1, where the electroniccontrol unit comprises: memory; and one or more processors, coupled tothe memory, to: break down at least a portion of a larger molecule fuelinto a smaller molecule fuel; heat the smaller molecule fuel to asupercritical temperature; mix exhaust with the heated smaller moleculefuel to produce an exhaust-supercritical fuel mixture; inject theexhaust-supercritical fuel mixture; compress the exhaust-supercriticalfuel mixture with air; ignite the compressed fuel using laser light;combust the compressed fuel with the air; and output power and exhaust.5. The system of claim 1, where mixing the exhaust stream with the fuelproduces a two phase mixture.
 6. The system of claim 1, where theelectronic control unit varies the compression ratio depending upon thefuel.
 7. The system of claim 1, where at least one of the one or moresupercritical fuel injectors includes a de Laval nozzle.
 8. A methodcomprising: providing an magnesium alloy engine block cast as amono-block to receive fuel and air as input, and output power andexhaust; breaking down, via a fuel reconditioning system, at least aportion of a larger molecule fuel into a smaller molecule fuel;splitting, via an exhaust splitter, the exhaust into two or more exhauststreams; heating, via a heat exchanger, the smaller molecule fuel usingat least one of the exhaust streams; mixing, via a mixer, at least oneof the exhaust stream with the heated smaller molecule fuel to producean exhaust-supercritical fuel mixture; injecting, via supercritical fuelinjectors, the exhaust-supercritical fuel mixture into engine block;compressing, in the engine block, the exhaust-supercritical fuel mixtureand the air; igniting, via an optical ignition system and in the engineblock, the compressed fuel; combusting, in the engine block, thecompressed fuel with air to produce the power and exhaust; andcontrolling, via an electronic control unit, at least one of the othersteps.
 9. The method of claim 8, where the engine block has a ceramicinner core.
 10. The method of claim 9, where the ceramic inner corecomprises a ceria stabilized tetragonal zirconia polycrystal.
 11. Themethod of claim 8, further comprising: controlling, by the electroniccontrol unit to: break down at least a portion of a larger molecule fuelinto a smaller molecule fuel; heat the smaller molecule fuel to asupercritical temperature; mix exhaust with the heated smaller moleculefuel to produce an exhaust-supercritical fuel mixture; inject theexhaust-supercritical fuel mixture; compress the exhaust-supercriticalfuel mixture with air; ignite optically the compressed fuel; combust thecompressed fuel with the air; and output power and exhaust.
 12. Themethod of claim 8, where mixing the exhaust stream with the fuelproduces a two phase mixture.
 13. The method of claim 8, where theelectronic control unit varies the compression ratio depending upon thefuel.
 14. The method of claim 8, where the electronic control unitcontrol the temperature of the fuel exiting the heat exchanger tobetween 560-580° C.
 15. A non-transitory computer readable mediumstoring instructions, the instructions comprising: one or moreinstructions which, when executed by one or more processors, cause theone or more processors to: break down at least a portion of a largermolecule fuel into a smaller molecule fuel via a fuel reconditioningsystem; heat the smaller molecule fuel to a supercritical temperaturevia a fuel heater; mix exhaust from an engine block with the heatedsmaller molecule fuel to produce an exhaust-supercritical fuel mixturein a mixer; inject the exhaust-supercritical fuel mixture into theengine block via one or more supercritical fuel injectors; compress theexhaust-supercritical fuel mixture with air in the engine block; ignitethe compressed fuel in the engine block via an optical ignition system;combust the compressed fuel with air in the engine block; and outputpower and exhaust from the engine block.
 16. The non-transitory computerreadable medium of claim 15, where the engine block has a ceramic innercore.
 17. The non-transitory computer readable medium of claim 16, wherethe ceramic inner core comprises a ceria stabilized tetragonal zirconiapolycrystal.
 18. The non-transitory computer readable medium of claim15, further comprising: controlling, by the electronic control unit to:break down at least a portion of a larger molecule fuel into a smallermolecule fuel; heat the smaller molecule fuel to a supercriticaltemperature; mix exhaust with the heated smaller molecule fuel toproduce an exhaust-supercritical fuel mixture; inject theexhaust-supercritical fuel mixture; compress the exhaust-supercriticalfuel mixture with air; ignite optically the compressed fuel; combust thecompressed fuel with the air; and output power and exhaust.
 19. Thenon-transitory computer readable medium of claim 15, where mixing theexhaust stream with the fuel produces a two phase mixture.
 20. Thenon-transitory computer readable medium of claim 15, where theelectronic control unit varies the compression ratio depending upon thefuel.